1. Field of the Invention
The present invention relates to a coupling apparatus.
2. Description of the Related Art
Coupling apparatuses are used for detachably connecting objects (hereinafter referred to as “objects to be connected”) each other. A coupling apparatus which includes an annular coupling body having a proximal end part attached to a predetermined part of an object to be connected and a distal end part positioned opposite to the proximal end part; and a plurality of fitting projections projecting in an axial direction of the coupling body from a plurality of predetermined circumferential positions on the distal end part of the coupling body, each fitting projection having an engaging hook projecting in one predetermined circumferential direction from its projecting end, is well known by, for example Japanese Patent Application KOKAI Publication No. 9-119577.
In a case that the predetermined parts of two objects are connected each other, the proximal end part of the coupling body of the conventional coupling apparatus as described above is attached to the predetermined part of each of the two objects to be connected. And, the coupling apparatus on the predetermined part of one object to be connected and that on the predetermined part of the other connecting member are approached coaxially to each other until the fitting projections of the distal end part of the coupling body of the one coupling apparatus fit into the fitting recesses defined between the fitting projections of the distal end part of the coupling body of the other coupling apparatus. Next, the coupling body of the one coupling apparatus is rotated in a predetermined circumferential direction relative to that of the other coupling apparatus, thereby engaging the engaging hooks of the fitting projections of the one coupling apparatus with those of the other coupling apparatus. As a result, the two coupling apparatuses are prevented from moving in directions along which the two coupling apparatuses are separated from each other, the two objects to be connected at the predetermined parts of which the two coupling apparatuses are attached are connected each other.
To disconnect the connection of such two conventional coupling apparatuses, the two coupling apparatuses are operated in reverse order to that described above.
Such a conventional coupling apparatus as described above further includes a structure as described below to prevent accidental disconnection of such two conventional coupling apparatuses.
A first disconnection preventing structure is a rotation preventing structure provided for each of the coupling bodies of the two coupling apparatuses to prevent rotation of the coupling bodies of the two coupling apparatuses after the two coupling apparatuses are connected together.
A second disconnection preventing structure is an elastic body which is provided at the end surface of the distal end part of the coupling body of each of the coupling apparatuses and which functions to move the coupling apparatuses away from each other in the axial directions thereof when the coupling apparatuses are coupled with each other to increase friction applied to the engaging hooks of the fitting projections of the coupling apparatuses.
In the conventional coupling apparatus as described above, the coupling body, the fitting projections, and the engaging hooks are formed integrally. And, when the above described conventional coupling apparatus falls on, for example, a hard floor or a road, or when two of the above described conventional coupling apparatus are strongly struck against each other, the fitting projections or engaging hooks of the coupling apparatus may be deformed or damaged. In such a case, the two coupling apparatuses can not be coupled with each other in the above described manner, so that the whole of the damaged coupling apparatus is replaced with a new one.
In addition, the more the diameter of the coupling body increase, the more the process of the fitting projections and engaging hooks formed integrally with the coupling body increase to rise a cost needed for the process.